Expandable pockets made of multiple pieces of material, such as a front panel, a back panel, and an accordion-pleated spine to fasten the panels together are known. However, such multi-piece folders are relatively difficult to manufacture. For example, multi-piece, expandable folders are hand-assembled by gluing the front and back panels to the spine, which decreases the rate of production. An additional drawback of conventional multi-piece folders arises during use. For example, when the folder is filled with documents or other materials, tears occur at stressed locations, particularly glued locations such as where the panels are adjoined to the spine.
U.S. Pat. No. 5,711,750 to Christensen et al. and U.S. Pat. No. 5,720,427 to Kachel et al. assigned to Smead Manufacturing Company, and hereinafter referred to as “the Smead patents,” disclose a plurality of embodiments of reinforced expandable pockets. According to one of the embodiments, disclosed in FIGS. 21 and 22, a pocket is manufactured by folding a single sheet of material. The pocket shown in FIG. 22, comprises a front cover 242 formed by two side panels 202 and 204, and a short panel 210, and a back panel formed by two side panels 206 and 208 and a short panel 214. Short panel 210 is located between the side panels 202 and 204, and the side panels and short panel are glued together to form the front cover; similarly, short panel 214 extends between the side panels 206 and 208, and the side panels and short panel are glued together to form the back cover. The short panels each extend from the spine and extend along the entire length of the bottom of the pocket.